[FLINK-16913][configuration] Support more getters in the ReadableConfigToConfigurationAdapter

[dawidwys]

What is the purpose of the change

Support all getters in ReadableConfigToConfigurationAdapter. It fixes configuring RocksDBStateBackend from flink-conf.yaml. In 1.11, we fix the issue by using the ReadableConfig directly for configuration. In 1.10.1 we don't want to change PublicEvolving interface.

Verifying this change

This change is already covered by existing tests.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[dawidwys]

cc @aljoscha @carp84

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[aljoscha]

Looks good, but a test would probably be in order.

[carp84]

Sorry but just noticed this one, here is my belated +1 and thanks for the fix @dawidwys !